Journal of Ethology

, Volume 30, Issue 2, pp 247–254

Male-biased sex ratio increases female egg laying and fitness in the housefly, Musca domestica

  • Juli Carrillo
  • Anne Danielson-François
  • Evan Siemann
  • Lisa Meffert
Article

Abstract

A biased operational sex ratio (OSR) can have multiple, confounding effects on reproductive fitness. A biased OSR can increase harassment and mating activity directed towards potential mates but may also increase the ability of potential mates to choose a good partner if lower quality mates are screened out through competitive interactions. Additionally, a biased OSR may affect reproductive fitness through changes in male ejaculate content or in female reproductive response. We quantified how a male-biased OSR (1:1, 2:1, or 5:1 male to female) affected the size of a female’s first egg clutch and her offspring’s survivorship in the housefly, Musca domestica. A male-biased OSR increased female fitness: females laid more eggs in their first clutch, had increased offspring survivorship at a 2:1 versus 1:1 OSR, and had equivalent fitness with a 5:1 male to female OSR. Courtship activity increased when the OSR was male-biased but was not a significant predictor of female fitness. Trials where females chose their mates versus trials where a random male was chosen for them had equivalent first clutch sizes and offspring survivorship. These results suggest that there are cryptic effects from a male-biased OSR on female fitness that are most likely driven by pre-copulatory social environment.

Keywords

Competition Courtship Sex ratio OSR Sexual conflict Indirect effects Clutch size 

Copyright information

© Japan Ethological Society and Springer 2011

Authors and Affiliations

  • Juli Carrillo
    • 1
  • Anne Danielson-François
    • 1
    • 2
  • Evan Siemann
    • 1
  • Lisa Meffert
    • 1
  1. 1.Department of Ecology and Evolutionary BiologyRice UniversityHoustonUSA
  2. 2.Division of Biology, Department of Natural SciencesUniversity of Michigan-DearbornDearbornUSA

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